Differentially pumped reactive gas injector

ABSTRACT

One process that may be used to remove material from a surface is ion etching. In certain cases, ion etching involves delivery of both ions and a reactive gas to a substrate. The disclosed embodiments permit local high pressure delivery of reactive gas to a substrate while maintaining a much lower pressure on portions of the substrate that are outside of the local high pressure delivery area. The low pressure is achieved by confining the high pressure reactant delivery to a small area and vacuuming away excess reactants and byproducts as they leave this small area and before they enter the larger substrate processing region. The disclosed techniques may be used to increase throughput while minimizing deleterious collisions between ions and other species present in the substrate processing region.

BACKGROUND

Fabrication of semiconductor devices typically involves a series ofoperations in which various materials are deposited onto and removedfrom a semiconductor substrate. One technique for material removal ision beam etching, which involves delivering ions to the surface of asubstrate to physically and/or chemically remove atoms and compoundsfrom the surface in an anisotropic manner. The impinging ions strike thesubstrate surface and remove material through momentum transfer (andthrough reaction in the case of reactive ion etching).

SUMMARY

Certain embodiments herein relate to methods and apparatus forperforming ion beam etching to remove material from the surface of asubstrate. In various cases, an injection head may be used to deliverreactants at a local high pressure while maintaining a lower pressure inthe greater substrate processing area outside of the injection head. Thelow pressure may be maintained by applying vacuum pressure in areassurrounding or abutting the local high pressure reactant delivery areaof the injection head. This processing scheme allows low pressure ionbeam processing with high pressure local reactant delivery, therebyreducing processing times and improving throughput.

In one aspect of the embodiments herein, an apparatus is provided forremoving material from a semiconductor substrate. The apparatus mayinclude a reaction chamber; a substrate support for supporting thesubstrate in the reaction chamber; an ion source configured to deliverions toward the substrate support; an injection head for providingreactants to a surface of the substrate when the substrate is positionedon the substrate support, the injection head including: asubstrate-facing region including (i) a reactant outlet region of areactant delivery conduit, and (ii) a suction region coupled to a vacuumconduit; and a movement mechanism for moving the injection head withrespect to the substrate support.

The reactant delivery conduit may be configured to couple with a linefrom a reactant source. Similarly, the vacuum conduit may be configuredto couple with a line to a vacuum pump. The substrate-facing region ofthe injection head may include a terminus of the reactant deliveryconduit and a terminus of the vacuum conduit, and the termini may besubstantially coplanar in some cases. The ion source typically includesa plasma generator for generating a plasma. In various cases the ionsource also includes electrodes for extracting ions from the plasma anddirecting the ions toward the substrate support. In some cases, twoelectrodes are used. In other cases, three electrodes are used. Incertain cases, four or more electrodes are used.

In certain embodiments, the substrate support, injection head, and/ormovement mechanism may be configured to maintain a separation distancebetween the injection head and the surface of the substrate when thesubstrate is positioned on the substrate support. The separationdistance may be about 1 cm or less, for example about 10 mm or less, orabout 5 mm or less, or about 2 mm or less, or about 1 mm or less. Otherseparation distances may be used, as well. The separation distance maybe actively controlled through feedback from a distance sensor in somecases.

The suction region typically abuts the reactant outlet region. In someembodiments the suction region surrounds or substantially surrounds thereactant outlet region. A second suction region may be coupled to thevacuum conduit in some cases. The second suction region typically abutsthe suction region. In some cases the second suction region surrounds orsubstantially surrounds the suction region. By using one or more suctionregions that abut and/or surround the reactant outlet region, excessreactant gases may be removed from the chamber (through the suctionregion(s)) before such reactants escape into the larger substrateprocessing region, where the reactants could undesirably collide withions in the ion beams.

The reactant outlet region may have a variety of shapes. In some casesthe reactant outlet region has a circle or oval shaped cross-sectionwhen viewed from above. In other cases, the reactant outlet region has apolygon shaped cross-section when viewed from above. In certainembodiments, the reactant outlet region is long and thin, having a slitshaped cross-section when viewed from above. The length of the reactantoutlet region may be smaller than, about equal to or greater than adiameter of a standard substrate to be processed in the apparatus. Inparticular cases, the length of the reactant outlet region may be atleast about equal to or greater than the diameter of a standardsemiconductor substrate to be processed in the apparatus. For instance,the standard semiconductor substrate may have a diameter of about 200mm, about 300 mm, or about 450 mm. This relatively long length isparticularly relevant where the injection head is long and thin. Thereactant outlet region may have a width in a direction parallel to thesubstrate support, the width being between about 0.5 mm to 10 cm. Thereactant outlet region may be separated from the suction region by adivider having a width between about 0.5 mm and 2 cm, where the width ofthe divider separates the reactant outlet region from the suctionregion. In some cases the suction region and/or a second suction regionmay have a width between about 1 mm and 5 cm.

The apparatus may further include a shutter in some cases. The shuttermay be configured to modulate a flux of ions. The shutter may bepositioned between the ion source and the substrate support. In aparticular case, the shutter may be configured to modulate the flux ofions in a manner that permits certain ions to pass through the shutterwhile other ions are simultaneously prevented from passing through theshutter, where the ions that are prevented from passing through theshutter are those that would otherwise impact the injection head. Invarious cases the injection head may further include a housing coveringthe reactant delivery conduit and the vacuum conduit. The housing mayinclude an ion source-facing surface opposite the substrate-facingregion of the injection head, the ion source-facing surface including asputter-resistant material. In some cases the injection head may becoated on at least an upper surface with a sputter resistant material.The injection head may be configured in some embodiments to locallydeliver two or more separate reactants that substantially do not mixwith one another before delivery. In some cases a second injection headmay be provided for supplying an additional reactant gases.

The apparatus may further include at least one of a sensor, sensor head,detector, or detector head, which may be mounted on, adjacent to, orintegrated within the injection head. One or more of the sensors and/ordetectors may be configured to monitor at least one of (i) thereactants, (ii) one or more reactant byproducts, and/or (iii) thesubstrate, within the reactant outlet region. In these or other cases,one or more of the sensors and/or detectors may be configured to monitorat least one of (i) the reactants, (ii) reactant byproducts, and/or(iii) the substrate, within the suction region. Further, in these orother cases, one or more of the sensors and/or detectors may beconfigured to monitor at least one of (i) the reactants and/or (ii)reactant byproducts, in the vacuum conduit. And in some cases, one ormore of the sensors and/or detectors may be configured to monitor atleast one of (i) the reactants, (ii) reactant byproducts, and/or (iii)the substrate, proximate the injection head.

The injection head is typically configured to move with respect to thesubstrate surface. In some cases the apparatus includes a track formoving the injection head over the substrate along an axis. A vacuumcompatible X-Y stage may be used for moving the injection head over thesubstrate in some cases. Further, a rotation mechanism may be configuredto rotate the substrate under the injection head. In some embodiments, avacuum compatible articulating robot arm is used to move the injectionhead with respect to the substrate.

In some implementations, the injection head may be divided intosegments, the segments being configured to receive or experience (i)different reactants, (ii) different reactant flow rates, and/or (iii)different vacuum conductances. One or more of fixed orifices, variableorifices, and/or mass flow controllers may be used for independentlycontrolling the flow rate of reactant or the vacuum conductance suppliedor applied to each segment. The segments may be within the reactantoutlet region and/or within the suction region in various cases. Aheating and/or cooling element may be included in the injection head incertain embodiments. The injection head may be configured to pivot abouta point in some implementations. The width of the injection head may bevaried to provide uniform gas coverage over the surface of thesubstrate.

In various embodiments, the apparatus further includes a controller. Thecontroller may have instructions to deliver the reactant to thesubstrate surface in the reactant outlet region at a first pressurewhile simultaneously removing the reactant from the suction region. Thecontroller may have instructions to maintain a second pressure in thereaction chamber in areas outside of the reactant outlet region and thesuction region, where the second pressure is at least about 25 timeslower than the first pressure. In other cases, the second pressure maybe at least about 100 times lower than the first pressure, or at leastabout 500 times lower than the first pressure, or at least about 1000times lower than the first pressure, or at least about 2000 times lowerthan the first pressure, or at least about 3000 times lower than thefirst pressure. The controller may have instructions to move theinjection head with respect to the substrate. The instructions to movethe injection head with respect to the substrate may achievesubstantially uniform ion flux across the surface of the substrate whenaveraged over time during an etching operation. The instructions to movethe injection head with respect to the substrate may includeinstructions to move the substrate. Alternatively or in addition, theinstructions to move the injection head with respect to the substratemay include instructions to move the injection head. The controller mayalso have instructions to generate a plasma, apply a first bias to anextraction electrode, and apply a second bias to a focus electrode.

In another aspect of the disclosed embodiments, an apparatus forremoving material from a semiconductor substrate is provided, theapparatus including: a reaction chamber; a substrate support forsupporting the substrate in the reaction chamber; an ion or plasmasource configured to deliver ions toward the substrate support; aninjection head for providing reactants to a surface of the substratewhen the substrate is positioned on the substrate support, the injectionhead including: a substrate-facing region including (i) a reactantoutlet region of a reactant delivery conduit, and (ii) a suction regioncoupled to a vacuum conduit that is configured to remove excessreactants at a periphery of the substrate; and a movement mechanism formoving the injection head or the substrate support with respect to oneanother.

In another aspect of the disclosed embodiments, a method of removingmaterial from a semiconductor substrate is provided. The method mayinclude providing the substrate to a reaction chamber; exposing asurface of the substrate to ions emanating from an ion source; exposingthe substrate to a reactant gas to thereby allow the reactant gas tocontact a surface of the substrate in a reactant outlet area on a firstportion of the substrate surface, where the reactant gas is provided tothe reactant outlet area at a first pressure, while simultaneouslyremoving the reactant gas in a suction area on the substrate surface andsubstantially surrounding the reactant outlet area, where the reactionchamber is maintained at a second pressure outside of the reactantoutlet area and the suction area, where the second pressure is at leastabout 25 times lower than the first pressure; and removing the materialfrom the substrate as a result of exposure to the ions and exposure tothe reactant gas.

In some cases, the second pressure may be at least about 100 times lowerthan the first pressure, or at least about 500 times lower than thefirst pressure, or at least about 1000 times lower than the firstpressure, or at least about 2000 times lower than the first pressure, orat least about 3000 times lower than the first pressure. In certaincases the second pressure is about 10 mTorr or less, for example about 1mTorr or less.

The method may also include moving the reactant outlet area over thesubstrate surface. The reactant outlet area may be moved over thesubstrate surface in a manner that delivers the reactants in a spatiallyuniform manner when averaged over time. In other cases, the reactantoutlet area is moved over the substrate in a manner that deliversreactants in a spatially non-uniform manner when averaged over time.Moving the reactant outlet area over the substrate surface may includerotating the substrate. In these or other cases, moving the reactantoutlet area over the substrate surface may include scanning the reactantoutlet area over the substrate surface. In various implementations,exposing the substrate to the reactant gas includes: delivering thereactant gas to an injection head including a substrate-facing regionincluding: (i) a reactant outlet region of a reactant delivery conduit,where the reactant outlet region delivers reactants to the reactantoutlet area, and (ii) a suction region coupled to a vacuum conduit,where the suction region removes reactants in the suction area. Adistance between a lower surface of the injection head and the surfaceof the substrate may be maintained between about 0.1-5 mm while theinjection head delivers the reactant gas. A small separation distancehelps minimize escape of the reactants into the greater substrateprocessing region, where such reactant molecules can collide with theion beams.

Various types of ions may be used as desired. In some cases, the ionsare inert or non-reactive. In other cases the ions are reactive. Forinstance, in some cases the ions oxidize material on the substrate. Thereactant gas may react with the oxidized material on the substrate tothereby remove the oxidized material. In certain embodiments thereactant gas may include one or more gases selected from the groupconsisting of oxidizers, halogenators, reducing agents, complexingagents, acids, bases, alcohols, ketones, aldehides, or esters or anycombination thereof. Examples include but are not limited to: H₂O, H₂O₂,NO₂, NO, N₂O, CF₄, C₂F₆, CHF₃, SF₆, HF, HCl, HI, HNO₃, Cl₂, CClF₃,CCl₂F₂, HBr, Br₂, F₂, H₂, NH₃, methanol, ethanol, isopropanol, aceticacid, formic acid, carboxylic acid, acetone, methylethyl ketone, acetylacetone (acac), hydrofluoro acetone (hfac), formaldehyde, and butylacetate.

Exposing the substrate to ions may include, in various implementations,generating a plasma, extracting the ions from the plasma by applying afirst bias to an extraction electrode positioned between the plasma andthe substrate, and focusing the ions by applying a second bias to afocus electrode positioned between the extraction electrode and thesubstrate. Removing material from the substrate typically includesremoving at least a portion of a layer of material on the substrate. Thelayer of material may form a feature of a non-volatile memory device.The non-volatile memory device may be an MRAM device. The non-volatilememory device may be an FeRAM device. The non-volatile memory device maybe a PCM device. The non-volatile memory device may be a 3D stackedmemory device.

In certain embodiments, reactant pressure and/or reactant flow aremodulated to result in a uniform material removal rate over the surfaceof the substrate when averaged over time. In other embodiments, reactantpressure or reactant flow is modulated to result in a non-uniformmaterial removal rate over the surface of the substrate when averagedover time. Different reactant pressures or different reactant flow ratesmay be maintained within different segments in the injection head toresult in uniform material removal over the substrate surface whenaveraged over time. In other cases, different reactant pressures ordifferent reactant flow rates may be maintained within differentsegments in the injection head to result in non-uniform material removalover the substrate surface when averaged over time.

These and other features will be described below with reference to theassociated drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 presents a simplified view of a reaction chamber that may be usedfor performing ion beam etching.

FIGS. 2A-2C depict a substrate as it undergoes an ion beam etchingprocess according to one embodiment.

FIG. 3 presents a reaction chamber having an injection head fordelivering reactants at a local high pressure.

FIGS. 4A-4C depict a cross-sectional view of an injection head accordingto certain embodiments.

FIG. 4D illustrates a top down view and a side cross-sectional view ofan injection head having numerous independently controllable gasdelivery conduits.

FIG. 4E presents a top down view and a side cross-sectional view of aninjection head having numerous independently controllable vacuumsegments.

FIG. 4F presents a top down view of an injection head that covers thefull area of the substrate.

FIG. 4G presents a top down view of an injection head that is separableinto two halves and is opened by pivoting the halves, shown in a halfopened position.

FIGS. 4H and 4I present cross-sectional side views of the injectionheads shown in FIGS. 4F and 4G.

FIG. 5 presents modeling data related to the pressure experienced ineach of the different regions of the injection head shown in FIGS.4A-4C.

FIGS. 6A-6I illustrate certain example paths and movements that may betraced by an injection head as it moves with respect to a substratesurface.

FIGS. 7A and 7B depict injection heads that separately deliver multiplereactant gases at local high pressures according to certain embodiments.

DETAILED DESCRIPTION

In this application, the terms “semiconductor wafer,” “wafer,”“substrate,” “wafer substrate,” and “partially fabricated integratedcircuit” are used interchangeably. One of ordinary skill in the artwould understand that the term “partially fabricated integrated circuit”can refer to a silicon wafer during any of many stages of integratedcircuit fabrication thereon. A wafer or substrate used in thesemiconductor device industry typically has a diameter of 200 mm, or 300mm, or 450 mm. The following detailed description assumes the inventionis implemented on a wafer. However, the invention is not so limited. Thework piece may be of various shapes, sizes, and materials. In additionto semiconductor wafers, other work pieces that may take advantage ofthis invention include various articles such as printed circuit boards,flat panel displays, semiconductor packages, magnetic recording mediaand devices, optical devices, mirrors and other reflecting media, sheetmetal or other materials that are substantially planar, and the like.

In the following description, numerous specific details are set forth inorder to provide a thorough understanding of the presented embodiments.The disclosed embodiments may be practiced without some or all of thesespecific details. In other instances, well-known process operations havenot been described in detail to not unnecessarily obscure the disclosedembodiments. While the disclosed embodiments will be described inconjunction with the specific embodiments, it will be understood that itis not intended to limit the disclosed embodiments.

Ion beam etching is commonly used in fabrication of semiconductordevices. As mentioned above, ion beam etching involves removing materialfrom the surface of a substrate by delivering energetic ions to thesubstrate surface. Ion beam etching may be broadly categorized intoprocesses that solely involve inert ions (e.g., argon ions), andprocesses that involve reactive ions or chemical reactions initiated byions (e.g., oxygen ions, certain ionized compounds such asfluorine-containing ionized compounds, reactive or inert ions initiatinga chemical reaction with a reactant that is chemisorbed or physisorbedon the surface on the substrate). In both types of processes, ionsimpinge on the substrate surface and remove material through eitherdirect physical momentum transfer (sputtering) or a chemical reactioninitiated by the energy transfer from the ions (Reactive Ion BeamEtching). Reactive ion beam etching typically involves eitherutilization of an ion that in addition to a physical impact canchemically react with the substrate (such as oxygen, fluorine and thelike) or an inert ion that initiates a chemical reaction between thesubstrate and a reactant (such as an applied gas that is adsorbed on thesurface) or an ion that generates a reactive site on the surface of thesubstrate that reacts with an applied reactant coincident with orsubsequent to the generation of the reactant site, or any combination ofthereof.

Certain applications for ion beam etching processes relate to etching ofnon-volatile materials. In some cases, the material etched is aconductive material. In certain embodiments, the material is etched inthe context of forming a magneto-resistive random-access memory (MRAM)device, a spin-torque-transfer memory device (STT-RAM), a phase-changememory device (PSM), a non-volatile conductor (copper, platinum, gold,and the like). In other applications, the ability to control the ionincident angle to the substrate can be useful in generating 3D devicessuch as vertically stacked memory, FinFET devices or gate-all-aroundstructures.

When performing ion beam etching processes, it is desirable to promote ahighly uniform ion flux over the substrate surface. A high degree ofuniformity is beneficial in creating reliable devices across the entiresurface of the substrate. Further, it may be desirable in certain casesto promote a high ion flux and/or a high flux of a gas phase reactant.High flux can help maximize throughput. Another factor that affects thequality of the etching results is the ability to control the energy andangle at which the ions impact the surface. These factors are importantin forming features having desired dimensions and profiles.

FIG. 1 presents a simplified cross-sectional view of an apparatus 100for performing ion beam etching according to certain methods. In thisexample, substrate 101 rests on substrate support 103, which may beequipped with hardware (not shown) to provide electrical and fluidicconnections. The electrical connections may be used to supplyelectricity to the substrate support 103 in some cases, while thefluidic connections may be used to provide fluids used to control thetemperature of the substrate 101 and substrate support 103. Thesubstrate support 103 may be heated by a heater (not shown) or cooled bya cooling mechanism (not shown). The cooling mechanism may involveflowing cooling fluids through piping in or adjacent the substratesupport 103. In some cases a heater may heat the substrate to anelevated temperature that is at least about 100° C., for example atleast about 200° C., at least about 300° C., or at least about 400° C.In these or other cases, the heater may heat the substrate to atemperature of about 600° C. or less. Where a cooling mechanism is used,the cooling mechanism may cool the substrate to a temperature betweenabout room temperature to −100° C. The substrate support 103 may becapable of rotating and tilting at variable speeds and angles, asindicated by the double headed arrows in FIG. 1.

A plasma generation gas is delivered to a primary plasma generationregion 105. The plasma generation gas is energized by a plasma source107. In the context of FIG. 1, the plasma source 107 is a coil that actsas an inductively coupled plasma source. Other sources such ascapacitively coupled sources, microwave sources or arc dischargesources, liquid metal ion sources or field ionization sources may beemployed in appropriately designed reactors. Plasma forms in the primaryplasma generation region 105. An extraction electrode 109 contains aseries of apertures 110 through which ions are extracted. The bias V₁applied to the extraction electrode 109 acts to provide kinetic energyto the ion with respect to the substrate. This bias is generallypositive and can range between about 20-10,000 volts or more, and incertain cases ranges between 25-2,000 volts. Positive ions in the plasmaabove the extraction electrode 109 are attracted to the lower electrode113 by the potential difference between electrodes 109 and 113. Focuselectrode 111 is added to focus the ions, and if needed, repelelectrons. A bias V₂ on the focus electrode 111 can be either positiveor negative with respect to the extraction electrode 109, and in variouscases is biased negatively. The bias potential of focus electrode 111 isdetermined by the lensing characteristics of the focus electrode 111.Voltages on this electrode range from positive voltages above the biasV₁ (e.g., between about 1.5× to 10× the bias V₁), to negative voltages(e.g., between about −0.001× to −0.9× the bias V₁). Due to the differentpotentials applied to the different electrodes, a potential gradientexists. The potential gradient may be on the order of about 1000 V/cm.Example separation distances between neighboring electrodes fall betweenabout 0.1-10 cm, or for example about 1 cm. After the ions leave thebottom of the grounded lower electrode 113, they travel in a collimatedand focused beam.

The lower electrode 113 is grounded in many (but not all) cases. The useof a grounded lower electrode 113 in combination with a groundedsubstrate 101 results in a substrate processing region 115 that issubstantially field-free. Having the substrate located in a field-freeregion prevents electrons or secondary ions generated by collisions ofthe ion beam with residual gases or with surfaces in the reactionchamber from being accelerated towards the substrate, which couldotherwise cause unwanted damage or secondary reactions. Additionally itis important to prevent the substrate 101 from charging from the ionbeam itself, or from ejected secondary electrons generated during theion beam collision with the substrate. Neutralization is typicallyaccomplished by adding a low energy electron source (not shown) in thevicinity of the substrate 101. Since the positive charge on the ion, andthe ejected secondary electrons both charge the substrate positively,low energy electrons in the vicinity can be attracted to the positivelycharged surface and can neutralize this charge. Performing thisneutralization is much easier in a field free region.

In some applications it may be desirable to have a potential differencebetween the lower electrode 113 and substrate 101. For example, if verylow energy ions are required, it is difficult to maintain a wellcollimated beam at low energy over long distances due to mutualrepulsion of the positively charged ions (space-charge effects). Onesolution to this is to place a negative bias on the lower electrode 113with respect to substrate 101 (or conversely biasing substrate 101positively with respect to the lower electrode 113). This bias schemeinvolves extraction of the ions at higher energy and then slowing theions as they approach the substrate.

The apertures 110 in the extraction electrode 109, focus electrode 111and lower electrode 113 may be precisely aligned with one another.Otherwise, ions will be aimed incorrectly, and the on-wafer etchingresults will be poor. For instance, if a single aperture in the focuselectrode 111 is misaligned, it may result in one area of the substrate101 becoming over-etched (where too many ions are directed) and anotherarea of the substrate 101 becoming under-etched (where no ions or toofew ions are directed). As such, it is desirable for the apertures to bealigned with one another as much as possible. In various cases themisalignment between vertically adjacent electrodes is limited to about1% or less of the hole diameter (as measured by the distance of a linearshift in the position of the aperture as compared to the adjacentaperture).

Ion beam etching processes are typically run at low pressures. In someembodiments, the pressure may be about 100 mTorr or less, for exampleabout 10 mTorr or less, or about 1 mTorr or less, and in many casesabout 0.1 mTorr or less. The low pressure helps minimize undesirablecollisions between ions and any gaseous species present in the substrateprocessing region.

Unfortunately, the low pressure required in many reactive ion beametching applications limits the rate at which reactants can be deliveredto the substrate processing region. If reactants are delivered at a ratethat is too high, the pressure will rise and ion-gas collisions becomeproblematic. The low reactant flow rate results in a relatively lowthroughput process, because the chemical reactant/etchant is not presentat a sufficient partial pressure to effectively etch the surface in arapid manner.

Certain embodiments disclosed herein address this collision-throughputtradeoff by providing reactant gases to the surface of the substrate ata relatively high local pressure with an injection head whilemaintaining a relatively low pressure outside the injection head. Inoperation, the injection head may provide a large pressure gradientbetween a reactant delivery region of the injection head and the edge ofthe injection head. The injection head delivers reactants andsimultaneously vacuums away the excess reactant species and byproducts.This setup prevents most of the reactant gas load from entering theregion where such reactants are likely to collide with ions, andtherefore enables both lower pressure in the overall substrateprocessing region and higher pressure local reactant delivery. Theinjection head may be scanned over different parts of the wafer in sucha manner to uniformly deliver reactant gas to the substrate surface overtime. Although at any given time the scanned injection head is onlysupplying reactants at high pressures to a local portion of the wafer,the injection head scans over the surface of the substrate during theetching process such that, on average, the reactant gas is delivered ina uniform manner. Various scanning patterns may be used to provideuniform reactant delivery. Alternatively the injector head may cover theentire substrate, and may be alternately positioned over the substrate,then removed from the substrate.

One example process where the disclosed injection head may be beneficialinvolves etching a substrate as shown in FIGS. 2A-2C. FIG. 2A shows thesubstrate during an initial portion of the etching process. Thesubstrate has an underlying layer or layers 201, along with a partiallyexposed layer of cobalt platinum (CoPt) 202, with a patterned hard masklayer 204 thereon. In this example the hard mask layer is tantalum.Although these materials are provided as examples, the disclosedembodiments may be used to etch any of various materials that areetchable by a sequential combination of an ion beam and an appliedreactant. Example materials to be etched include but are not limited to:(1) semiconductors such as silicon, silicon-germanium, germanium, whichin some cases may be etched by a sequence of Cl₂, HCl, HBr, or Br₂ gasexposure followed by inert ion exposure (the inert ions may be, forexample, He, Ne, Ar, Kr, Xe, or a combination thereof); (2) metals suchas Cu, Fe, Co, Ni, Pd, or W, which may in some cases be oxidized with anoxygen ion beam, then reacted with an acid or an organic vapor such asacetyl acetone (acac), hydrofluoro acetone (hfac), or acetic acid orformic acid to form a volatile gas or high vapor pressure compound; (3)metals or semiconductors such as Si, SiGe, Ge, groups III-V elements,Pd, and Fe, which in some cases may be surface activated by an inert orreactive ion such as H, He, O, N, F, Cl, or Br ions, then chemicallyetched at the reactive site by application of a reactant gas or vaporsuch as F₂, HF, Cl₂, HCl, Br₂, HBr, NH₃, acetic acid, combinationsthereof, etc.

A plasma is generated in the primary plasma generation region above theset of electrodes. The gas used to generate the plasma in this exampleincludes oxygen, and the generated plasma therefore includes oxygenions. The oxygen ions travel through the extraction electrode, focuselectrode, and lower electrode, and impact the surface of the substrateas shown in FIG. 2A. After the ions impact the substrate surface for aperiod of time, an upper surface of the cobalt platinum material 202becomes oxidized material 206, as shown in FIG. 2B. The hard mask layer204 may resist oxidation. After exposure to the reactant gas, theoxidized material 206 is etched away, as shown in FIG. 2C.

In conventional methods, this etching may involve extinguishing theplasma, transferring the substrate to another processing chamber, andcontacting the substrate with oxide removal chemistry such as acetylacetone (acac), hydrofluoro acetone (hfac), or acetic acid. Othersubstrate materials may be removed by other compounds. In some cases,the removal occurs through wet chemistry methods.

In the disclosed embodiments, however, the extra steps such asextinguishing the plasma and transferring the substrate to a newprocessing chamber may be avoided. In one example, the injection headscans the surface of the wafer to deliver reactant gases or vapors atrelatively high local partial pressures (e.g., a partial pressure thatis at least about 10×, or at least about 100×, or at least about 500×,or at least about 1000×, or at least about 2000×, and in some cases atleast about 3000× the pressure in the substrate processing region) whilethe plasma is present in the primary plasma generation region and ionsare actively impacting the substrate surface. The reactant gas etchesthe oxidized material from the surface. In another example, theinjection head scans the surface of the wafer to deliver reactant gas atcertain times while ions are not actively impacting the surface. In onesuch example, the flow of ions into the substrate processing region ismodulated with a shutter, as shown in FIG. 3. In this way, the plasmacan remain ignited and the flow of ions can be shuttered on and off asneeded. The injection head may move to a location that is out of the way(i.e., not between the wafer and the electrodes) while the shutter isopen and ions are impinging on the substrate surface.

In some cases, the shutter may be configured to block ions passingthrough a certain portion of the electrodes while allowing ions to passthrough other portions of the electrode. Rather than acting like blindsthat all open and close together, the shutter in this case mayindependently block or unblock individual apertures in the electrodes.In this way, the flow of ions through each aperture may be turned on andoff. One advantage of this embodiment is that an aperture may beshuttered off only when an injection head is directly between thatparticular aperture and the substrate surface, while the apertureremains open during times when the injection head is not in the way.

Regardless of whether the injection head actively delivers reactant gasto the substrate while ions are impinging on the substrate, the use ofthe injection head allows for both parts of etching (ion delivery andchemical reactant delivery) to occur in the same chamber, withoutextinguishing the plasma.

For applications such as atomic layer etching (ALE), the disclosedembodiments are particularly useful, as they allow each portion of theprocess to be pressure optimized. ALE involves sequential delivery andadsorption of reactants, purging of excess reactants, and exposure to anenergy source to remove very thin layers (e.g., monolayers in somecases) of material. Often, such adsorption, purging and energy exposureoperations are performed in a cyclic manner to etch material on alayer-by-layer basis. The disclosed injection head and methods of usesubstantially open the available operating window for the pressure atwhich various gases are provided. Further, the disclosed techniques mayresult in ALE methods that use different timing sequences. For instance,reactant delivery, purging, and exposure to energy may all occursimultaneously on different portions of the wafer. Reactant delivery andpurging occur locally under the injection head, and exposure to energy(ions) occurs globally everywhere that the injection head doesn't block.Atomic layer etching methods are further discussed in the following U.S.Patents, each of which is herein incorporated by reference in itsentirety: U.S. Pat. No. 7,416,989, titled “ADSORPTION BASED MATERIALREMOVAL PROCESS”; U.S. Pat. No. 7,977,249, titled “METHODS OF REMOVINGSILICON NITRIDE AND OTHER MATERIALS DURING FABRICATION OF CONTACTS”;U.S. Pat. No. 8,187,486, titled “MODULATING ETCH SELECTIVITY AND ETCHRATE OF SILICON NITRIDE THIN FILMS”; U.S. Pat. No. 7,981,763, titled“ATOMIC LAYER REMOVAL FOR HIGH ASPECT RATIO GAPFILL”; and U.S. Pat. No.8,058,179, titled “ATOMIC LAYER REMOVAL PROCESS WITH HIGHER ETCHAMOUNT.”

FIG. 3 presents a simplified view of a reaction chamber 300 used forreactive ion beam etching in some implementations. A wafer 301 issupported on a pedestal such as an electrostatic chuck 302 in substrateprocessing region 303. Ions are generated, extracted, and focused in theion source 304. The ion source 304 may include a plasma generationregion and a series of electrodes as shown in FIG. 1, though other ionsources may also be used. The flow of ions emanating from the ion source304 may be shuttered on and off through optional ion shutter 305. Theinjection head 306 moves over the surface of the substrate 301 todeliver process gases under the injection head 306 at the local highpressure delivery region 307. The local high pressure region may also bereferred to as a reactant outlet region or reactant delivery region. Thelocal high pressure region may form part of a reactant delivery conduit,and may be coupled to a line that provides reactants to the injectionhead 306.

Low pressure is maintained in the substrate processing region 303 by theinjection head 306, which removes the local high pressure reactantsimmediately after they are delivered to the wafer 301. In particular,while the reactants are delivered in the local high pressure deliveryregion 307, the injection head 306 simultaneously applies a vacuum tothe regions surrounding or otherwise proximate to the local highpressure delivery region 307 (these surrounding regions are sometimesreferred to as pressure drop regions or suction regions), therebyremoving excess reactants before they enter the larger substrateprocessing region 303 outside of the injection head 306. The excessreactants are removed through vacuum connection (not shown). The vacuumconnection may be somewhat thin and flexible to allow the injection head306 to move over the surface of the wafer 301, or it may form a part ofthe injection head itself. The vacuum connection may be physicallyjoined with the lines used to deliver reactants such that the reactantdelivery lines and the vacuum connection move together (though theyremain functionally separated).

In some cases the injection head may be elongated to extend the entirewidth of the substrate, and the vacuum connection may be configuredin-line with the head. FIG. 3 may be interpreted in this way, with theinjection head 306 (as well as the reactant delivery line and vacuumconnection, which may form part of the injection head 306) extendinginto and out of the page. In this embodiment, the injection head maydeliver reactants to the entire surface of the wafer by scanning along asingle axis perpendicular to the length of the injector head (i.e., leftand right in FIG. 3) or along a pivot point. In this configuration thevacuum connection would not block the ion beam in regions outside of theinjection head itself. Further details of the injection head 306 arediscussed below.

FIGS. 4A-4C present simplified cross-sectional views of an injectionhead 400 passing over a wafer 401 according to certain embodiments. FIG.4A shows the injection head 400 and the components therein. FIG. 4B isprovided to illustrate certain dimensions of the injection head 400.FIG. 4C is provided to illustrate flow patterns through the injectionhead 400. Beginning with FIG. 4A, reactant gases are introduced to theinjection head 400 at reactant inlet 402. The reactant gases areintroduced to the local high pressure region R₀ (also referred to as areactant outlet region) at a relatively high pressure. A first dividerD₁ separates the local high pressure region R₀ from the first pressuredrop region R₁ (also referred to as a suction region), a second dividerD₂ separates the first pressure drop region R₁ from the second pressuredrop region R₂ (sometimes referred to as a second suction region), and athird divider D₃ separates the second pressure drop region R₂ from thesurrounding substrate processing region R₃. The dividers may be sheetsor other thin structures, and may be made of an etchant-resistantmaterial such as a polymer, ceramic, metal, or glass. Example materialsinclude aluminum, aluminum alloys, anodized aluminum, stainless steel,alumina ceramic, machinable glass ceramic, fused silica, inconel, monel,boro-silicate glass, vespel, Teflon or kapton, which may be chosen forthe particular etchant(s) being used.

Vacuum is applied to the first and second pressure drop regions R₁ andR₂ in order to vacuum away excess reactant delivered to the local highpressure region R₀. The vacuum is applied through vacuum connection 403.In a similar embodiment, the vacuum connection 403 extends into and outof the page, rather than extending off to the right as shown in FIGS.4A-4C. In one embodiment the local high pressure region R₀ may be acylindrically shaped region bounded on the sides by the first dividerD₁. The first and second pressure drop regions R₁ and R₂ may beannularly shaped to surround the local high pressure region R₀.Alternatively, each of the local high pressure region R₀ and the firstand second pressure drop regions R₁ and R₂ may be long and thin whenviewed from above (e.g., each having a substantially rectangularcross-section as viewed from above), each extending into/out of thepage.

A sputter resistant coating 404 may coat the injection head 400. Such asputter resistant coating 404 may be made from carbon (e.g., amorphouscarbon), or a material that, if sputtered, would not be considered acontaminate of the substrate material such as silicon, SiO₂, aluminum,or Al₂O₃, etc. The sputter resistant coating 404 may help minimize theamount of material that is sputtered off of the injection head 400. Theinjection head outer shell (under the sputter-resistant coating) may bemade from a polymer, ceramic, metal, or glass, with examples includingaluminum, aluminum alloys, anodized aluminum, stainless steel, aluminaceramic, machinable glass ceramic, fused silica, inconel, monel,boro-silicate glass, vespel, Teflon or kapton.

Another way to characterize the different relevant regions is by lookingat what is happening on the wafer itself. The portion of the waferlocated under the local high pressure region R₀ may be referred to as alocal high pressure area (also referred to as the reactant outlet area).The portion of the wafer located under the pressure drop regions R₁ andR₂ may be referred to as a pressure drop area, or two pressure dropsub-areas. These areas may also be referred to as suction areas. Theportion of the wafer that's not under the injection head may be referredto as the ion processing areas. The positions of the local high pressurearea, the pressure drop area and the ion processing area change as theinjection head moves over the surface of the wafer.

Those of ordinary skill in the art understand that any of a variety ofshapes may be used in a structure or structures for creating the localhigh pressure region R₀ and the first and second pressure drop regionsR₁ and R₂, so long as the pressure drop regions are designed orconfigured to vacuum away excess reactants and reactant byproducts afterthey are delivered to the local high pressure region R₀ and before theyenter the substrate processing region R₃. As such, the first pressuredrop region R₁ may surround or substantially surround the local highpressure region R₀, and the second pressure drop region R₂ may surroundor substantially surround the first pressure drop region R₁. The regionsmay be round/cylindrical as shown in FIGS. 4A-4C, or they may be anothershape (oval, square, rectangular, triangular, other polygonal shape,slit, etc.). The exposed area under R₀ may substantially smaller thanthe substrate, approximately equal to the substrate, or larger than thesubstrate. In a particular example the local high pressure region isshaped as a relatively long and thin slit, and the pressure drop regionabuts both sides of the slit. In this case, while the pressure dropregion may or may not entirely surround the local high pressure region(e.g., near the thin sides of the slit), such a pressure drop region maybe said to substantially surround the local high pressure region becausea substantial majority of the excess reactants are vacuumed away by thepressure drop regions proximate the long sides of the slit-shaped localhigh pressure region. In certain embodiments, one or both pressure dropregions surround at least about 70% (or at least about 90%) of theperimeter of the reactant delivery region. In a particular case one orboth pressure drop regions surround 100% of the perimeter of thereactant delivery region. In certain embodiments, the first pressuredrop/suction region is directly adjacent to the local highpressure/reactant delivery region. In certain embodiments, the secondpressure drop/suction region is directly adjacent the first pressuredrop/suction region.

Any number of separate pressure drop/suction regions may be used. Whiletwo pressure drop regions are shown in FIGS. 4A-4C, in some embodimentsonly a single pressure drop region is used. In other embodiments, two ormore pressure drop regions are used, for example three or more pressuredrop regions. In some embodiments, up to about 5 pressure drop regionsare used. The substrate processing region and the local high pressureregion are not considered to be pressure drop regions. Typically, anypressure drop region will be located proximate a local high pressureregion or another pressure drop region, and will have a vacuumconnection for removing excess reactants. The pressure drop regions actto sequentially reduce the pressure between adjacent regions.

FIG. 4B presents the injection head 400 illustrated in FIG. 4A, withcertain dimensions highlighted. W₀ represents the width of the localhigh pressure region R₀. W₁ and W₂ represent the thickness (outerdiameter minus inner diameter, where these regions are annularly shaped)of the first pressure drop region R₁ and the second pressure drop regionR₂, respectively. L₁, L₂, and L₃ represent the thicknesses of the firstdivider D₁, second divider D₂, and third divider D₃, respectively. Thedistance between the surface of the substrate 401 and the bottom of thedividers D₁-D₃ is marked h. The distance between the surface of thesubstrate 401 and the vacuum connection 403 is marked h. The height ofthe dividers is marked h_(D).

The width W₀ may be between about 0.5 mm to 10 cm. The thickness W₁ maybe between about 1 mm to 5 cm. Similarly, the thickness W₂ may bebetween about 1 mm to 5 cm. The W₁ and W₂ thicknesses may be the same ordifferent. In some cases, W₁ is larger than W₂, while in other cases W₂is larger than W₁. The thickness L₁ may be between about 0.5 mm to 2 cm.Similarly, the thickness L₂ may be between about 0.5 mm to 2 cm, and thethickness L₃ may be between about 0.5 mm to 2 cm. In some cases, L₁, L₂,and L₃ are substantially the same (e.g., they do not differ by more thanabout 5%). In other cases, these thicknesses may be different. Theheight g between the bottom of the dividers D₁-D₃ and the surface of thesubstrate 401 may be about 5 mm or less, for example about 2 mm or less,or about 1 mm or less. In some cases this distance g is between about0.1 mm to 5 mm. This distance should be relatively small to minimize theamount of excess reactant that escapes from the injection head and intothe substrate processing region. The height h may be between about 0 to5 cm

In some cases, the dividers D₁-D₃ have unequal length, and the distancebetween the bottom of each divider and the surface of the substrate isdifferent. Although not shown in FIG. 4B, in such an embodiment thedistance between the substrate surface and the first divider D₁ may bereferred to as g₁, the distance between the substrate surface and thesecond divider D₂ may be referred to as g₂, and the distance between thesubstrate surface and the third divider D₃ may be referred to as g₃. Itmay be desirable in certain embodiments that g₁ is largest and/or g₃ issmallest (when comparing g₁, g₂, and g₃). In this way, escape of excessreactants to the substrate processing region R₃ may be minimized. Byadjusting divider length, D₁-D₃, divider widths L₁-L₃, and divider gapsW₀-W₂, reactant gas residence times can be adjusted.

FIG. 4C illustrates flow patterns through the injection head 400. Alsonoted in FIG. 4C is the pressure experienced at each region. A pressureof P₀ is present in the local high pressure region R₀, a pressure of P₁is present in the first pressure drop region R₁, a pressure of P₂ ispresent in the second pressure drop region R₂, and a pressure of P₃ ispresent in the substrate processing region R₃. P₀ is the highestpressure and P₃ is the lowest pressure. Reactants are delivered to thehigh pressure region R₀ at pressure P₀, where they act on the substratesurface to etch away material. Excess reactants and reaction productsthen pass under the first divider D₁ and into the first pressure dropregion R₁ where they are vacuumed away by the vacuum connection 403.Species that are not vacuumed up in the first pressure drop region R₁instead pass under the second divider D₂ and into the second pressuredrop region R₂ where they are vacuumed away by the vacuum connection403. A very small amount of species may pass under the third divider D₃and into the substrate processing region R₃. However, the amount of suchspecies that escape to the substrate processing region R₃ is quitesmall, and does not generally pose a problem in terms of ion collisions.In certain embodiments, P₀ may be at least about 1000 times higher thanP₃. In one example, P₀ is at least about 10 times higher than P₁, whichis at least about 10 times higher than P₂, which is at least about 10times higher than P₃. In these and other cases, the pressure may drop bya factor of at least 5 between adjacent regions.

In certain embodiments, the injection head covers a fraction of thesubstrate's surface area of between about 0.1% and 50%, or between about1% and 10%. This fraction may represent the portion of the substrateblocked from ion contact and/or the portion of the substrate exposed tothe reactant delivery portion and suction portion(s) of the injectionhead. In other embodiments, the injection head covers 100% or more ofthe substrate.

FIG. 4F presents an embodiment of an injection head that can cover 100%or more of the substrate area. The injection head shown in FIG. 4F iscircular=, but could be any shape provided it covers all of thesubstrate surface. In some cases the overall shape of the injection headwhen viewed from above matches the shape of the substrate (e.g., acircular injection head for a circular substrate, as shown in FIG. 4F, asquare injection head for a square substrate, etc.). The injection headcan then be moved off of the substrate to allow ion exposure on thesubstrate surface, then moved back over the substrate to expose thesubstrate to the reactant. This movement may occur through a lineartranslation or through pivoting (or through a combination of the two).While the injection head is shown to include two halves, these halvesmay be joined together to form a single unitary injection head. Wherethe injection head is separated into halves (or other partialcomponents), the halves may split/pivot open as shown in FIG. 4G.Presented in FIG. 4G, the injection head is separated into 2 halves,each of which is on a separate pivot. Here, the injection head is shownin a partially open position. Alternatively the injector head can bedivided into any number of sections and pivot points, for example,thirds, quarters, etc. In this embodiment, the various portions of theinjection head rotate over the substrate to provide reactant gas atlocal high pressure, and then rotate away from the substrate to allowion exposure on the substrate surface. In this example, the highpressure region acts on the entire substrate surface at once. Thedistance between the substrate surface and the ceiling of the reactionhead is maintained relatively small such that the injection head candeliver reactants to a small volume above the substrate surface. Excessreactants are removed at the periphery of the substrate, as shown inFIGS. 4G-4I.

FIG. 5 presents computer modeling data related to the injection headshown in FIGS. 4A-4C. In particular, FIG. 5 relates the pressure in eachregion of the injection head for flow rates between about 0-1000 sccm.The data are modeled assuming that the reactant delivered at highpressure is N₂ (larger molecules would result in even greater pressuredrops). Further, the data are modeled assuming that W₀₌₅ cm, W₁=W₂=1 cm,L₁=L₂=L₃=1 cm, h=1 cm, and g=1 mm. The molecular/transition flow wascalculated using slit conduction approximations based on the descriptionin “A low conductance optical slit for windowless vacuum ultravioletlight sources” by R. A. George et al., Journal of Physics E: ScientificInstruments, Volume 4, Number 5 (1971).

For any given flow rate modeled in FIG. 5, the pressure drops by morethan an order of magnitude between adjacent regions of the injectionhead. As a result, the pressure drops from about 2 Torr at P₀ to about0.00025 Torr at P₃, which represents an overall decrease of about99.9875%. Another way to characterize the results is that the pressuredrops by a factor of about 8,000 in this example.

Similar modeling simulations were run for injection heads havingdifferent dimensions. While the dimensions affected the degree ofpressure drop, each case showed a considerable reduction of pressurebetween adjacent regions. Larger L₁, L₂ and L₃ dimensions (thickness ofthe dividers D₁-D₃) result in larger pressure drops. Similarly, smallerg distances between the bottom of the dividers D₁-D₃ and the substratesurface result in larger pressure drops. Various other modifications maybe made to affect the degree of pressure drop experienced in theinjection head.

Another advantage provided by the injection head is the ability toperform atomic layer etching. Atomic layer etching represents a processwhereby a controlled amount of material is removed each pass in amulti-pass process wherein one of the processes is fully or partiallyself-limiting. Atomic layer removal processes are further discussed inthe following Patents and Patent Applications, each of which is hereinincorporated by reference in its entirety: U.S. Pat. No. 8,608,973, U.S.Pat. No. 8,617,411, and PCT Patent Application No. PCT/US2012/046137. Inone embodiment, the scanning injection head generates a localizedadsorption of a reactive chemical on a substrate surface that issubsequently removed by the ion beam once the head is moved away fromthe localized area. In a second embodiment, the ion beam generates areactive surface that reacts with reactant chemicals in the head oncethe injection head is scanned over the reactive surface.

As mentioned above, the injection head moves over the surface of thewafer to deliver reactant gases. Ions may or may not be activelyimpacting the surface of the wafer while the injection head deliversreactant gases, depending on the particular embodiment. A robot arm orother movable mechanical support may be used to hold and move theinjection head over the wafer surface. The robot arm may move theinjection head over the surface in a single dimension or in twodimensions, and may be an articulating robot arm. Movement of theinjection head with respect to the substrate surface may be accomplishedby moving the injection head, moving (e.g., rotating) the wafer, orthrough a combination of such movements. The robot arm may also move theinjection head in a third dimension (lifting it away from the substratesupport), for example when a wafer is being loaded or unloaded. In someembodiments, the vacuum connection and/or reactant delivery connectionsare integrated into the robot arm or other mechanical support. In othercases, the vacuum connection and/or reactant gas connections and robotarm are separate. Like the injection head, the robot arm may be coatedwith a sputter resistant coating. In some implementations, the robot armor other scanning mechanism used to support the injection head ispermanently mounted on a portion of the reaction chamber (e.g., attachedto the reaction chamber sidewall). In other implementations, the robotarm or other scanning mechanism may be mounted on a track that allowsthe arm to easily move around the circumference of the wafer. In eithercase, the robot arm or scanning mechanism may includeconnections/joints/points of movement to allow the injection head tomove over the surface as desired.

In certain embodiments, the injection head is long and narrow, as shownin FIG. 6E, for example. In various cases, the long length of theinjection head extends the full length/diameter of the substrate, andthe narrow width of the injection head extends a fraction of thesubstrate width, as shown. In this embodiment the injection head isscanned back and forth in the direction perpendicular to the long axisof the injection head so as to fully cover the substrate during eachpass as shown in (e.g., in FIG. 6E the injection head scans left andright). In these or other cases, the injection head may have a lengththat is greater than or equal to the substrate physical length (e.g.,equal to or greater than about 200 mm, 300 mm, or 450 mm in many cases).In various embodiments the injection head has a length that is betweenabout 1 to 10 cm longer than the substrate length. The injection headmay have a width that is between about 1 to 15 cm, for example betweenabout 2 to 5 cm. The scanning of the head may be accomplished using alinear actuator, such movement shown in FIG. 6E or using or one morepivot point, as shown in FIGS. 6G and 6H. The substrate may also berotated under the injection head, as shown in FIGS. 6F-6I. In certainembodiments, the injection head width may be varied to compensate forscan speed or other variations that may occur, for example, in a singlepivot head configuration. An example of an injection head havingvariable width is shown in FIG. 6H. Alternatively additional pivotpoints may also be used. In the case of 2 pivot heads, as shown in FIG.6I, the injector head can be scanned linearly across the substrate.

Two different but related uniformity considerations are important withregard to the injection head. First, reactant gas delivery flux(mass/unit area) through the injection head should be uniform over theface of the wafer when averaged over time during an etching process.Second, ion delivery flux from the ion source should be uniform over theface of the wafer when averaged over time. When the injection head/robotarm/vacuum connection blocks the line of sight between the ion sourceand a local portion of the wafer, such local portion of the wafer is notimpacted by the ions. As such, the injection head, robot arm, and vacuumconnection may be configured to provide delivery of reactant gases aswell as ions in a spatially uniform manner when averaged over time.

Various scanning patterns may be used to move the injection head overthe surface of the substrate to achieve such spatially uniform reactantgas/ion delivery. FIGS. 6A-6I present example scanning patterns that maybe used in some embodiments. FIGS. 6A-6D present various tracks that aninjection head may take over the surface of a substrate. These scanningpatterns may be particularly relevant where the injection head has ageometry that involves movement in two dimensions to cover the entiresubstrate surface. In some cases, an X-Y stage may be used to move theinjection head over the substrate. FIGS. 6E-6F depict elongated scanninginjection heads and their movement over the surface of a substrate invarious embodiments. Because the injection heads in these cases are atleast as long as the substrate diameter, the movement over the substrateis relatively simple.

FIG. 6A shows a spiral scanning pattern, FIGS. 6B and 6C showline-by-line linear patterns, and FIG. 6D shows a radial pattern. Otherpatterns may be used as well. In some cases, the pattern is configuredsuch that the local high pressure region reaches all or substantiallyall the wafer. A portion of the local high pressure region and/or aportion of the pressure drop regions may cross over the edge of thewafer in certain patterns, as shown in FIG. 6B. In other cases, thepattern may be designed to place the local high pressure region and/orthe pressure drop regions entirely within the edge of the wafer at alltimes, as shown in FIG. 6A. The injection head may move in straightlines, curves, spirals, etc. The injection head may move along a radiusof the wafer, as shown in FIG. 6D. In some embodiments, orbitalmovements are used. In FIG. 6E, an elongated injection head having arectangular/slit shaped cross section when viewed from above is scannedback and forth in a direction perpendicular to the elongation length. InFIG. 6F, an elongated injection head is scanned back and forth in adirection perpendicular to the elongation length and the substrate isrotated. In FIGS. 6G and 6H, the elongated injection head is pivotedabout a fixed pivot point to scan back and forth over the substrate,with or without substrate rotation. In FIG. 6I, the use of two pivotpoints allows the injection head to scan linearly over the substratesurface without using a dedicated linear actuator.

In some cases, it may be beneficial to deliver reactants in a spatiallynon-uniform way when averaged over time. Spatially non-uniform reactantdelivery may be used to combat other spatial non-uniformities that arisein a process. For instance, if spatially uniform reactant deliveryresults in over-etching the center of the substrate and under-etchingthe edges of the substrate, additional etchant gas or other process gasmay be provided to the edges of the substrate compared to the center, tothereby balance out the process and provide spatially uniform results.Related issues such as non-uniformities in the ion beam or processingtool may similarly be compensated for with non-uniform reactant delivery(e.g., by adjusting the etchant rate/flow/pressure/scanning speed, etc.over different parts of the substrate and/or during different portionsof the etching process). Further, non-uniform reactant delivery andnon-uniform etching results may be beneficial in compensating forprevious spatial non-uniformities arising from other processes. Forinstance, a previous processing step may introduce a systemic error (ornon-systemic error if such error is pre-measured and quantified) such asa variation in mask width (line width error) or a variation in filmthickness. Where such error/spatial non-uniformity is known, the etchingprocess can be configured to compensate for the non-uniformity.

Another reason that non-uniform reactant delivery and non-uniformetching may be beneficial relates to process development and tuning. Forinstance, non-uniform reactant delivery may be used to perform multipleexperiments on a single substrate. The reactant delivery conditions maybe adjusted independently on different parts of the substrate (e.g.,delivering reactants at different flow rates and/or different pressuresand/or different scanning speeds to different parts of the wafer), andthe results may be observed and compared. This technique may reduce thenumber of substrates needed to test various reaction conditions.

A further benefit that may arise from non-uniform reactant delivery andnon-uniform etching relates to forming particular features/shapes whileetching. For instance, it may be desirable to etch a line having adifferent profile on each side (e.g., a vertical profile on a first sideand a sloped profile on the other side). In order to accomplish thisetching shape, a variable flow rate of reactant may be used. A firstflow rate may be used while the substrate is tilted in a firstdirection, and a second flow rate may be used while the substrate istilted in a second direction (e.g., the second direction may be oppositethe first direction). This asymmetrical etching technique may be used toetch features having non-uniform profiles.

The linear speed at which the injection head moves may be between about0-500 cm/s, for example between about 1-100 cm/sec, or between about5-100 cm/sec. Where different portions of the injection head move atdifferent speeds (e.g., in the embodiments shown in FIGS. 6G and 6H),the speeds listed above may correspond to the fastest-moving portion ofthe injection head. The injection head may scan over the entire surfaceof the wafer at least once within a time period between about 0.5-10 s.The substrate rotation rate may be between about 0 and 500 RPM, forexample between about 0 and 10 RPM. In some cases the linear or angularspeed is constant, while in other cases the speed is variable. Variablespeed may be helpful in designing patterns that provide spatialuniformity over time. For example, in patterns where the injection headcovers certain parts of the wafer more often (e.g., in FIG. 6D thecenter of the substrate is affected by the injection head more oftenthan each outer portion of the wafer), the injection head may scan oversuch high frequency portions at a greater speed than other portions. Inthis way, less material is delivered to that portion of the substrate ineach instance, and the total gas delivery is more spatially uniformoverall. In some embodiments, the reactant delivery rate varies as afunction of position on the substrate surface. For example, a higherdelivery rate may be employed in regions where the head moves fastest.In another example, reactant delivery uniformity is achieved by movingthe injection head at a constant linear and/or angular speed, and usinga higher rate of reactant delivery when the injection head is acting onportions of the wafer that are covered by the injection head less often(e.g., if the injection head moves inward and outward along the radiusof the substrate while the substrate rotates, a controller may use anoscillating delivery rate that is higher toward the edge of thesubstrate and lower toward the center of the substrate, since the centerarea is contacted more frequently than any given edge area).

In certain cases where an elongated injection head is used (e.g., FIGS.6E-6I), the length of the head may be divided into zones/segments. Eachzone may have an independent reactant supply pressure or suctionconductance thereby allowing control of the amount of reactant andpressure of the reactant across the substrate surface. Adjustment of theflow rate, pressure and conductance difference between zones may bestatic or dynamic. In the case of dynamic adjustment, each zone may haveindependent reactant supply control through, for example, independentmass flow controllers, variable orifices. Alternatively or in addition,each zone may have independent vacuum pumping through, for example, aset of butterfly valves. In certain embodiments the zones along thelength of an elongated injection head have both independent vacuumpumping and reactant injection capability. FIG. 4D shows a top view andside view of an injection head 450 having a plurality of independentlycontrollable gas injectors 477, each fed by an independentlycontrollable gas delivery line 478. For ease of illustration, the gasdelivery lines 478 are not shown in the top view. Though not shown, thegas delivery lines 478 may be covered by a housing that may be integralwith the injection head 450. FIG. 4E shows a top view and side view ofan injection head 460 having independently controllable vacuum regions461. The vacuum pressure in each of the vacuum regions 461 may beindependently controlled. The various vacuum regions 461 are divided bydividers 462, which in some cases may have any of the divider dimensionslisted above with respect to FIGS. 4A-4C.

While the injection head has thus far been described as a mobileinjection head that moves over the surface of a static substrate, otherdesigns are possible. For example, in some embodiments the wafer movesunder the injection head. Such wafer movement may be instead of or inaddition to movement of the injection head. The substrate supportmechanism in such cases may be configured to rotate and/or translate thewafer. The wafer may rotate at a speed between about 0-200 RPM. Orbitalprocessing may be accomplished using concerted motion of both thesubstrate and the injection head.

In some processes, it may be beneficial to deliver more than one gaseousreactant at a local high pressure. A number of different techniques maybe used to deliver more than one reactant. In one example, the injectionhead is configured as described above (e.g., with respect to FIG. 4A),and the two or more reactants are mixed before or as they are deliveredto the local high pressure region. In another example, a multipleinjection heads are provided to deliver each individual reactant. Themultiple injection head embodiment may be particularly useful where thereactant gases are expected to deleteriously react with one another, orwhere it is desired that the reactants be delivered in a sequentialmanner. In another example, a single modified injection head is used toseparately provide each reactant.

A modified injection head may take various forms. FIG. 7A presents oneexample of an injection head 700 that may be used to separately delivera number of reactants. The injection head 700 of FIG. 7A is similar tothe injection head 400 of FIG. 4A. However, the injection head 700 ofFIG. 7A includes two inlets 702A and 702B for separately deliveringreactant A and reactant B to the wafer 701. The two inlets 702A and 702Bare separated by a divider D₄, which cuts the local high pressure regioninto two local high pressure regions R_(0A) and R_(0B). Reactant A isdelivered at a high pressure in the first local high pressure regionR_(0A), and reactant B is delivered at a high pressure in the secondlocal high pressure region R_(0B). As shown, each local high pressureregion R_(0A) and R_(0B) may have the same amount of area exposedsubstrate surface. However, the divider D₄ may be positioned off-centerto thereby allow different reactant areas over the substrate (in otherwords, R_(0A) and R_(0B) may have different sizes). In one embodiment,the local high pressure regions R_(0A) and R_(0B) have substantiallysemi-circular cross sections when viewed from above, and the pressuredrop regions R₁-R₂ have substantially annular cross sections when viewedfrom above. In another embodiment, R_(0A), R_(0B), and R₁-R₂ each haveelongated cross-sections, for example substantially rectangular crosssections, when viewed from above. In such a case, the various regionsmay extend into and out of the page in FIG. 7A. Where this is the case,it may be beneficial to design the reactant delivery lines and vacuumconnection such that they are in-line with the various elongatedsections of the injection head. In such a design, the arrow pointing tothe vacuum pump may extend into or out of the page, along the length ofthe injection head, rather than off to the right, as shown.

Reactant A and reactant B may be provided at the same local highpressure, or at different pressures. Excess reactants are removed in thepressure drop regions R₁ and R₂. In another embodiment, reactant B isprovided via a reactant delivery region that substantially surrounds thereactant delivery region of reactant A. For example, the reactantdelivery region of reactant B may fully encircle that of the reactantdelivery region for reactant A.

While reactants A and B are provided separately, they may mix with oneanother to some degree in the pressure drop regions R₁ and R₂. Themixing may be minimized by dividing the pressure drop regions intodifferent angular portions. For instance, the pressure drop regions mayeach be divided into two sub-regions, a first sub-region that isproximate the first local high pressure zone R_(0A) and a secondsub-region that is proximate the second local high pressure zone R_(0B).The first sub-region may primarily remove excess reactant A and thesecond sub-region may primarily remove excess reactant B. Of course,additional angularly distinct sub-regions may be used to furtherminimize mixing of the reactants. If mixing of the reactants within thevacuum connection 703 is a problem, separate vacuum connections may beprovided to connect to each distinct portion of the apparatus. Thisembodiment may be modified to separately provide any number of reactantsat different pressures, simply by changing the shape of the inlets andthe divider separating the inlets. In one example, the divider D₄ has across-shaped cross section when viewed from above, each quadrant of thecross being configured as an inlet to provide one of four differentreactants.

FIG. 7B presents an additional embodiment of an injection head 710 thatmay be used to separately deliver two different reactants A and B. Likethe embodiment of FIG. 7A, the high pressure region is split into afirst local high pressure region R_(0A) for delivering reactant A, and asecond local high pressure region R_(0B) for delivering reactant B.However, FIG. 7B includes an additional central reactant removal regionR_(V) separating the two local high pressure regions R_(0A) and R_(0B).Near the wafer, the central reactant removal region R_(V) is bounded onone side by divider D₅ and on the other side by divider D₆ (thus, inthis example the portion of R_(V) near the substrate has a rectangularcross-section when viewed from above). The central reactant removalregion R_(V) is connected with the vacuum pump through connection 711 toremove excess reactants and help prevent mixing of the reactants as theyare actively adsorbing onto or otherwise contacting the surface of thesubstrate 701. This embodiment may be modified to provide any number ofreactants. Moreover, the central reactant removal region R_(V) may bedivided into additional regions to further minimize the likelihood thatreactants are able to mix in the gaseous (non-adsorbed) state. Like theembodiment of FIG. 7A, the injection head in the embodiment of FIG. 7Bmay have a substantially circular cross section or an elongated,substantially rectangular cross-section when viewed from above. Wherethe injection head is substantially circular, the pressure drop regionsR₁ and R₂ may be annularly shaped, as viewed from above. Where theinjection head is elongated, the pressure drop regions R₁ and R₂ mayalso be elongated, extending along the length of the entire injectionhead, with the R₁ regions abutting the entire length of the local highpressure regions R_(0A) and R_(0B), and the R₂ regions abutting theentire length of the R₁ regions.

As mentioned above, another way to separately provide two or morereactants is to use two or more injection heads. The two or moreinjection heads may be completely separate, or they may share one ormore components such as the vacuum connection, robot arm, etc. Further,two or more injection heads may be used to separately provide reactantsto different parts of the wafer, even where both injection heads deliverthe same reactant gas.

The disclosed embodiments may be used to deliver any gas phase reactantat a local high pressure to the surface of a substrate. In someembodiments, the gas phase reactant delivered by the injection headcomprises one or more of oxidizers, halogenators, reducing agents,complexing agents, acids, bases, alcohols, ketones, aldehides, or estersor any combination thereof. Examples include but are not limited to:H₂O, H₂O₂, NO₂, NO, N₂O, CF₄, C₂F₆, CHF₃, SF₆, HF, HCl, HI, HNO₃, Cl₂,CClF₃, CCl₂F₂, HBr, Br₂, F₂, H₂, NH₃, methanol, ethanol, isopropanol,acetic acid, formic acid, carboxylic acid, acetone, methylethyl ketone,acetyl acetone (acac), hydrofluoro acetone (hfac), formaldehyde, andbutyl acetate, and any combination thereof. Further, any source and typeof ions may be used. The ions may be inert, reactive, non-reactive or acombination of inert reactive and non-reactive ions. Example inert ionsinclude noble gases such as argon, helium, neon, krypton, xenon, etc.Example reactive ions include nitrogen, hydrogen, oxygen, fluorine,bromine, iodine, sulfur, etc. Example of non-reactive ions include:nitrogen, silicon, carbon, germanium, boron, and aluminum. Inert ionsmay be particularly suitable for etching non-volatile materials, forexample in processes involved in fabricating MRAM and FeRAM devices. Onthe other hand, reactive ions may be especially suitable for etchingsemiconductor materials, which may involve processes for fabricatinglogic and memory devices.

In some embodiments, the flow of the gas used to generate the ions isbetween about 0.1-1000 sccm. In these or other embodiments, the flow ofreactant gas through the injection head is between about 0.1-5000 sccm,for example between about 10-500 sccm. Reactants may be provided to alocal high pressure region of an injection head at a pressure betweenabout 0.1-100 Torr, for example between about 1-50 Torr in some cases.In the example related above with respect to FIGS. 2A-2C where oxygenions act to oxidize a metal surface and a reactive gas (e.g., aceticacid) is used to remove the oxidized metal, the flow rate of acetic maybe between about 10 sccm-500 sccm, and the oxygen ion current densitymay be between about 0.1-20 mA/cm².

In some embodiments the injection head may be heated or cooled. Heatedinjector heads may be needed for injecting reactant vapors (to preventcondensation of the reactant) or for providing some thermal energy toeffect the surface reaction on the substrate. In other embodiments, theinjector head may be cooled to promote surface adsorption of thereactant on the substrate.

The injection head may optionally contain one or more diagnosticelements or end point detectors integrated into head or connected to thehead. The detectors or diagnostic elements may be placed in the localhigh pressure zone, in one or more of the intermediate pressure zones,in the vacuum exhaust region, or outside but adjacent to the head.Diagnostic or endpoint detectors can include: residual gas analysis,FTIR spectrometers, ellipsometry, extinction coefficient measurement, orother optical film thickness measurement device, atomic absorptionspectrometers, optical emission spectrometers, ion inducedilluminescence spectrometers, faraday cups, interferometers, quartzcrystal microbalances, AFM probes, magnetic field sensors, eddy currentsensors, dielectric-resonators or other contactless sheet resistancesensors.

While the embodiments have been described in the context of a reactiveion beam etching process, they are not so limited. It is expected thatthe disclosed injection head will be useful in any application thatinvolves delivering one or more high pressure reactants to a surface ina local manner where it is desired that the overall pressure (outsidethe injection head) remains low.

The apparatus used for performing the disclosed embodiments oftenincludes a system controller having programming to control the etchingprocess. The controller may execute system control software, which maybe stored in a mass storage device, loaded into a memory device, andexecuted on a processor. The software may be transferred over a networkin some cases. Various process tool component subroutines or controlobjects may be written to control operation of the process toolcomponents necessary to carry out various process tool processes. Thesystem control software may be coded in any suitable computer readableprogramming language. In some embodiments, the system control softwaremay include input/output control (IOC) sequencing instructions forcontrolling the various parameters discussed herein. The systemcontroller may also be associated with other computer software and/orprograms, which may be stored on a mass storage device or memory deviceassociated with the controller. Examples of programs or sections ofprograms for this purpose include a substrate positioning program, aplasma gas control program, a reactant gas control program, a pressurecontrol program, a temperature control program, and a plasma controlprogram.

A substrate positioning program may include code for process toolcomponents that are used to load and unload the substrate onto thesubstrate support, and to control the spacing between the substrate andother parts of the processing apparatus such as the injection head. Aplasma gas control program may include code for controlling thecomposition and flow rates of gas(es) used to generate the plasma fromwhich ions are extracted. A reactant gas control program may includecode for controlling the composition, flow rate, and pressure at whichreactant gases are delivered through the injection head (or to/throughother portions of the apparatus). A pressure control program may includecode for controlling the pressure at which individual reactants aredelivered, the pressure at which reactants are removed, and the pressureat which the substrate processing region is maintained. A temperaturecontrol program may include code for controlling heating and/or coolingequipment used to maintain the substrate, substrate support, and/orsubstrate processing region at a particular temperature. A plasmacontrol program may include code for generating the plasma at certainpowers and frequencies.

The system control software may include instructions for deliveringreactants at the flow rates and/or pressures disclosed herein. Suchinstructions may relate to delivery of a gas used to generate plasma(from which ions are extracted), or they may relate to delivery of oneor more gases through the one or more injection heads. The systemcontrol software may also include instructions for removing excessreactants at a certain vacuum pressure. Further, the system controlsoftware may include instructions related to movement of the injectionhead with respect to the substrate. For instance, the instructions mayrelate to moving the injection head, moving the substrate, or both. Invarious cases the system control software includes instructions to movethe injection head with respect to the substrate in a manner thatdelivers reactants in a spatially uniform manner when averaged overtime. The instructions may also relate to any operations needed to loadand unload the substrate.

The system control software may further include instructions formaintaining the substrate processing region at a certain pressure, forexample any of the low pressures listed herein. The system controlsoftware also typically includes instructions for controlling the timingof the etching process. In many cases the controller also controls thebias applied to each of the electrodes. As such, the system controlsoftware may include instructions for applying a first bias to theextraction electrode, a second bias to the focus electrode, and a thirdbias (or ground conditions) to the lower electrode andsubstrate/substrate support. In some embodiments, the instructionsfurther include maintaining the substrate and/or substrate processingregion at a particular temperature through heating or cooling.

Where a shutter is used to modulate ion flux, the system controlsoftware may include instructions to modulate the ions by opening andclosing the shutter at desired times. In a particular embodiment, thesoftware includes instructions to open the shutters (thereby allowingions to impinge on the wafer surface) only when the injection head isnot actively present on the surface. In a related embodiment, thesoftware includes instructions to maintain certain shutters open andcertain shutters closed, the closed shutters being those that wouldotherwise allow ions to impinge on the injection head, and the openshutters being those that allow ions to impinge directly on the wafersurface (i.e., ions are allowed to hit the substrate surface but not theinjection head).

With respect to plasma generation, the system control software mayinclude instructions for providing a plasma generation gas at aparticular flow rate, temperature, and/or pressure. The instructions mayfurther relate to the amount of power (e.g., RF power) used to generatethe plasma, and the frequency at which such power is delivered.

In some embodiments, a user interface may be associated with a systemcontroller, the user interface may include a display screen, graphicalsoftware displays of the apparatus and/or process conditions, and userinput devices such as pointing devices, keyboards, touch screens,microphones, etc.

In many embodiments, the system controller is used to adjust otherprocess parameters. Such parameters may include, but are not limited to,reactant gas compositions, flow rates, and pressures, plasma generationgas composition, flow rates, and pressures, pressure in the substrateprocessing region, bias applied to the individual electrodes,temperature, plasma conditions (e.g., frequency and power), position ofthe wafer and/or injection head, etc.

Signals for monitoring the process may be provided by analog and/ordigital input connections of the system controller from various processtool sensors. The signals for controlling the process may be output onthe analog and digital output connections of the controller.Non-limiting examples of process tool sensors that may be monitoredinclude mass flow controllers, pressure sensors, thermocouples, etc.Appropriately programmed feedback and control algorithms may be usedwith data from these sensors to maintain process conditions. In certainembodiments, a distance sensor may be used to provide feedback forcontrolling the distance between the substrate and the injection head.

The various hardware and method embodiments described above may be usedin conjunction with lithographic patterning tools or processes, forexample, for the fabrication or manufacture of semiconductor devices,displays, LEDs, photovoltaic panels and the like. Typically, though notnecessarily, such tools/processes will be used or conducted together ina common fabrication facility.

Lithographic patterning of a film typically comprises some or all of thefollowing steps, each step enabled with a number of possible tools: (1)application of photoresist on a workpiece, e.g., a substrate having asilicon nitride film formed thereon, using a spin-on or spray-on tool;(2) curing of photoresist using a hot plate or furnace or other suitablecuring tool; (3) exposing the photoresist to visible or UV or x-raylight with a tool such as a wafer stepper; (4) developing the resist soas to selectively remove resist and thereby pattern it using a tool suchas a wet bench or a spray developer; (5) transferring the resist patterninto an underlying film or workpiece by using a dry or plasma-assistedetching tool; and (6) removing the resist using a tool such as an RF ormicrowave plasma resist stripper. In some embodiments, an ashable hardmask layer (such as an amorphous carbon layer) and another suitable hardmask (such as an antireflective layer) may be deposited prior toapplying the photoresist.

It is to be understood that the configurations and/or approachesdescribed herein are exemplary in nature, and that these specificembodiments or examples are not to be considered in a limiting sense,because numerous variations are possible. The specific routines ormethods described herein may represent one or more of any number ofprocessing strategies. As such, various acts illustrated may beperformed in the sequence illustrated, in other sequences, in parallel,or in some cases omitted. Likewise, the order of the above describedprocesses may be changed.

The subject matter of the present disclosure includes all novel andnonobvious combinations and sub-combinations of the various processes,systems and configurations, and other features, functions, acts, and/orproperties disclosed herein, as well as any and all equivalents thereof.

What is claimed is:
 1. An apparatus for removing material from asemiconductor substrate, the apparatus comprising: a reaction chamber; asubstrate support for supporting the substrate in the reaction chamber;an ion or plasma source configured to deliver ions toward the substratesupport; an injection head for providing reactants to a surface of thesubstrate when the substrate is positioned on the substrate support, theinjection head comprising: a substrate-facing region comprising (i) areactant outlet region of a reactant delivery conduit, and (ii) asuction region coupled to a vacuum conduit, wherein the ion or plasmasource is positioned above the injection head such that ions from theion or plasma source impinge downward upon an upper surface of theinjection head; and a movement mechanism for moving the injection heador the substrate support with respect to one another.
 2. The apparatusof claim 1, wherein the substrate-facing region comprises a terminus ofthe reactant delivery conduit and a terminus of the vacuum conduit, andwherein the termini are substantially coplanar.
 3. The apparatus ofclaim 1, wherein the substrate support, injection head, and/or movementmechanism are configured to maintain a separation distance between theinjection head and the surface of the substrate when the substrate ispositioned on the substrate support, wherein the separation distance isabout 1 cm or less.
 4. The apparatus of claim 3 wherein the separationdistance is about 2 mm or less.
 5. The apparatus of claim 3 wherein theseparation distance is actively controlled through feedback from adistance sensor.
 6. The apparatus of claim 1, wherein the suction regionsubstantially surrounds the reactant outlet region.
 7. The apparatus ofclaim 1, further comprising one or more additional suction regionscoupled to one or more vacuum conduits, wherein the additional suctionregions substantially surround the suction region.
 8. The apparatus ofclaim 1, wherein a length of the reactant outlet region is at leastabout equal to or greater than a diameter of a substrate to be processedin the apparatus.
 9. The apparatus of claim 1, wherein the reactantoutlet region has a width in a direction parallel to the substratesupport, the width being between about 0.5 mm to 10 cm.
 10. Theapparatus of claim 1, wherein the reactant outlet region is separatedfrom the suction region by a divider having a width between about 0.5mm-2 cm, the width of the divider separating the reactant outlet regionfrom the suction region.
 11. The apparatus of claim 1, wherein thesuction region has a width between about 1 mm-5 cm.
 12. The apparatus ofclaim 1, wherein the injection head further comprises a housing coveringthe reactant delivery conduit and the vacuum conduit.
 13. The apparatusof claim 1, wherein the upper surface of the injection head is coatedwith a sputter-resistant material.
 14. The apparatus of claim 1, whereinthe injection head is configured to locally deliver two or more separatereactants that substantially do not mix with one another beforedelivery.
 15. The apparatus of claim 1, further comprising additionalinjection heads for providing additional reactant gases.
 16. Theapparatus of claim 1, wherein at least one of a sensor, sensor head,detector, or detector head is mounted on, adjacent to, or integratedwithin the injection head.
 17. The apparatus of claim 16, wherein one ormore of the sensors and/or detectors are configured to monitor at leastone of (i) the reactants, (ii) one or more reactant byproducts, and/or(iii) the substrate.
 18. The apparatus of claim 1, further comprising arotation mechanism configured to rotate the substrate under theinjection head.
 19. The apparatus of claim 1 wherein the injection headis divided into segments, the segments being configured to receive orexperience (i) different reactants, (ii) different reactant flowrates,and/or (iii) different vacuum conductances.
 20. The apparatus of claim19, further comprising one or more of fixed orifices, variable orifices,or mass flow controllers for independently controlling the flowrate ofreactant or vacuum conductance supplied or applied to each segment. 21.The apparatus of claim 1, further comprising a heating element and/orcooling element for heating and/or cooling the injection head.
 22. Theapparatus of claim 1, wherein the injection head is configured to movewithin a plane parallel to the substrate support.
 23. The apparatus ofclaim 1, further comprising a controller having instructions to deliverthe reactant to the surface of the substrate in the reactant outletregion at a first pressure while simultaneously removing the reactantfrom the suction region.
 24. The apparatus of claim 23, wherein thecontroller further has instructions to move the injection head withrespect to the substrate or the substrate with respect to the injectionhead.
 25. An apparatus for removing material from a semiconductorsubstrate, the apparatus comprising: a reaction chamber; a substratesupport for supporting the substrate in the reaction chamber; an ion orplasma source configured to deliver ions toward the substrate support;an injection head for providing reactants to a surface of the substratewhen the substrate is positioned on the substrate support, the injectionhead comprising: a substrate-facing region including (i) a reactantoutlet region of a reactant delivery conduit, and (ii) a suction regioncoupled to a vacuum conduit that is configured to remove excessreactants at a periphery of the substrate, wherein the ion or plasmasource is positioned above the injection head such that ions from theion or plasma source impinge downward upon an upper surface of theinjection head; and a movement mechanism for moving the injection heador the substrate support with respect to one another.